1. Field of the Invention
This invention relates to a semiautomatic paper setting system for use in typewriters, printers and the like, and, in particular, to a printer provided with a semiautomatic paper setting system in which a carriage is moved to a predetermined position prior to advancement of a paper around a platen roller to insure proper setting of paper at all times.
2. Description of the Prior Art
When certain information is to be typed or printed on a cut sheet of paper, the sheet must be first set in a typewriter or printer. FIG. 1 shows a typical prior art printer 1 in perspective with its top cover removed. As shown, the printer 1 includes a carriage 4 having thereon a print head 2 for forming printed characters on a cut sheet of paper and a guide plate 3 for guiding the advancement of the sheet as printing proceeds. The carriage 4 rides on a guide rail 7 fixedly provided in the printer 1 and extending in parallel with a platen roller 8 which is rotatably supported in the printer 1. The carriage 4 is fixedly connected to a wire 6 which is operatively connected to a carriage drive motor 5. Thus, when the motor 5 is driven to rotate, the carriage moves along the rail 7 in a reciprocating manner. On the other hand, the platen roller 8 is driven to rotate intermittently by means of a line-feed motor 9 thereby advancing the sheet of paper placed around the platen roller 8.
Also provided in the printer 1 are pressure rollers 10 and 11, which are operatively associated with a pressure roller lever 13. When the lever 13 is pushed forward, the pressure rollers 10 and 11 are moved away from the platen roller 8; whereas, when the lever 13 is pulled toward the operator, the pressure rollers 10 and 11 are brought into contact with the platen roller 8 under pressure as shown in FIG. 2. Moreover, paper bail rollers 12 are provided as rotatably supported by a bail lever 14 which is pivoted on the housing of the printer 1. The bail lever 14 may also take two positions; that is, the operative position in which the bail rollers 12 are lightly pressed against the platen roller 8 and the inoperative position in which the bail rollers 12 are spaced apart from the platen roller 8. Although not shown specifically, the printing position is defined between the pressure rollers 10 and the bail rollers 12 since the sheet of paper may be properly held at the desired position in this region.
In order to set a sheet of paper in the printer 1 prior to the printing operation, both of the levers 13 and 14 must first be operated so that the pressure rollers 10,11 and the bail rollers 12 are located away from the platen roller 8. Then a sheet of paper is manually inserted, and after correcting skewness, the levers 13 and 14 are again operated to bring the pressure rollers 10,11 and bail rollers 12 in the respective operative positions. Such a manual paper setting is quite cumbersome and the setting condition often changes from one sheet to another thereby causing misalignment in printing lines between different sheets. It is true that several attempts have been and are being made to alleviate the cumbersomeness of paper setting and to improve the printing quality in typewriters, printers and the like; however, none of these attempts is satisfactory and there has been a need for the advent of an improved system for setting a sheet of paper in typewriters, printers and the like.